1. Field of the Invention:
The present invention relates to a photographic film strip, a photographic film cassette containing the same, and a camera for use therewith. More particularly, the present invention relates to a photographic film strip which is convenient to handle, and a photographic film cassette and a camera for use therewith.
2. Description of the Related Art:
At present various types of photographic film strips (hereinafter referred to as film) are available. A 35 mm photographic film or 135-type photographic film, which is used with a 35 mm camera or a half-size camera, is contained in a cylindrically shaped photographic film cassette in the form of a roll on a spool which is rotatably contained in a cassette shell. A trailer, or inward-rolled end of the photographic film, strip is anchored on the spool. It is known to utilize anchoring claws formed on a spool core engaged with holes formed in the trailer to anchor the trailer to the spool. It is also known to form holes in a leader of the strip in a similar manner for anchoring the leader to a processing device, or the like.
Also, a return cassette or preserving cassette with which a developed strip of photographic film can be returned to a customer and preserved has been disclosed in Japanese Patent Laid-open Publication No. 3-179341 and Japanese Patent Application No. 3-193431, both being commonly assigned co-pending applications. (The former corresponds to U.S. Ser. No. 07/584,017, filed on Sep. 18, 1990 and patented as U.S. Pat. No. 5,083,155 on Jan. 21, 1992, and to German Patent Application No. P 40 29 555.9 filed on Sep. 18, 1990. The latter corresponds to U.S. Ser. No. 07/910,914 filed on Jul. 8, 1992, and to German Patent Application No. P 42 22 462.4 filed on Jul. 8, 1992.) The preserving cassette is constituted of a spool for winding the developed strip of photographic film, a cassette shell for rotatably containing the spool with the developed photographic film strip, and a structure for causing the photographic film strip to advance out of a passage defined in the cassette shell when the spool is rotated in the unwinding direction.
When the cassette containing the photographic film strip, after exposure, is forwarded to a photo laboratory, then an operator, in a preparatory step, splices a leader of the photographic film strip to a leader sheet, for which splicing tape is used. The leader sheet is provided with perforations adapted to handling in a photographic film processor. Prior to splicing, the photographic film strip is advanced from the cassette shell, and a tongue of its leader having a smaller width is cut off. The cassette with the leader sheet attached thereto is then loaded in a holder of the processor. The perforations in the leader sheet mesh with claws of a transporting mechanism of the processor, and the film is then transported to the inside of the processor. Transportation of the leader sheet pulls the photographic film strip out of the cassette. A cutter is actuated to cut the fully drawn photographic film strip away from the spool. The photographic film strip is then passed through relevant processing tanks of the processor, and automatically developed.
The developed strip of photographic film is then subjected to making photoprints in a photographic printer. To contain the developed photographic film strip in the above-mentioned preserving cassette, the leader sheet is removed and anchor holes are punched in the shortened trailer to anchor it on the spool of the preserving cassette. After anchoring the new holes on the spool, the developed photographic film strip is wound on the spool, and returned to the customer contained in the preserving cassette.
As suggested in U.S. Pat. No. 4,834,306, a known photographic film cassette includes photographic film strip positioned so that a leader does not protrude from a cassette shell prior to loading a camera with it. Such a cassette is easily loaded into a camera. A simple film-advancing mechanism of the camera is typically used with this type of cassette, and includes a construction which rotates a spool to unwind the photographic film strip, thereby causing the leader to move through a passageway for the photographic film strip and exist from the cassette. This type of photographic film strip has, as disclosed in U.S. Pat. No. 4,908,641, take-up holes formed in a leader to be engaged with claws of the take-up spool of the camera, and entering perforations, one for each original frame, regularly formed along one lengthwise edge of the strip for positioning each frame opposite an exposure aperture within the camera. An image of a subject to be shot is created in each frame on the photographic film strip.
It has also been proposed to provide the above-mentioned preserving cassette with a structure for causing the photographic film strip to advance outward when the spool is rotated in the unwinding direction, which is useful e.g. for automatically making extra prints.
U.S. Pat. No. 4,878,075 discloses a camera in which a photographic film strip having a magnetic recording area is used, and which is provided with a magnetic head that reads data concerning a type, sensitivity etc. of the photographic film strip from the recording area, and/or writes thereto photo-taking data concerning exposure of the photographic film strip to create frames. It is also known to provide the camera with a light emitting construction such as a light-emitting diode (LED) and thereby record photo taking data optically or photographically on the strip.
When using the above-mentioned preserving cassette for the photographic developed film strip, it is very difficult for an operator of the photo laboratory to punch anchoring holes in the shortened trailer of the photographic film strip. Should the holes not be in precise positions with respect to the claws of the spool, the trailer may fail to be anchored thereon. Should the photographic film strip be forcibly wound around the spool without positive anchoring of the trailer, the photographic film strip would be detached from the spool in posterior processes, e.g. extra printing. This can cause difficulties in the various apparatuses associated with processing. Also, the developed strip of photographic film may be damaged (e.g. bad scratches or cracks may be formed) while punching hole sin the trailer. If such a damaged film is wound up fully in the preserving cassette, the cracks and the like in the photographic film cassette may cause the leader would within the preserving cassette to fail to be advanced outward therefrom when the spool is rotated in the unwinding direction.
Also, the conventional photographic film strip provided with the take-up holes and entering perforations must be used with a camera having a detector circuit for discriminating the perforations from the take-up holes. The detector circuit requires an ID or the like and thus the camera is expensive.
The camera for use with the photographic film strip having a recording area also has disadvantages in that the positioning of relevant structures is complicated. The use of the metering perforations of the photographic film strip requires a photo sensor disposed in the camera for detecting them. The use of the magnetic recording area requires a magnetic head in the camera for recording and/or reading data. the photo sensor and the magnetic head are arranged around the exposure aperture of the camera, along with an autofocus (AF) device, a portion of a viewfinder, and a mechanism for transmitting the photographic film strip. Accordingly, incorporation of the photo sensor adapted to the metering perforations and the magnetic head in the camera requires the camera to be large. The same problem remains when the magnetic head is replaced with an LED.